This invention relates to the locating of the center of a recorded track and more particularly but not by way of limitation to locating the center of a recorded magnetic track on a rotating magnetic storage disk unit.
In the use of flexible media substrates recording accuracy is presently limited by media dimensional changes as a result of temperature and humidity variations. Also interchange of recorded media between units may also be limited by individual positioner accuracies and initial calibration. The flexible media grows and contracts with atmospheric changes. Thus the radius of any prerecorded track also changes. Therefore, it is difficult to determine how far the recorded track has moved from its nominal position. Compensation for this change requires that the read/write transducer positioning system must be capable of compensating motion.
Signal amplitude as a function of the transducer position is shown in the drawings and has a shape in a curve which is largely independent of the disk media and the transducer position. Typically the curve shape will be symmetrical with peak and skirt positions ill defined. Signal amplitude will be the same for a given displacement either side of the nominal track centerline. This fact is used as a bases for establishing the track center and the system and method described herein. Heretofore, there have been various types of systems and methods for positioning a transducer over a recorded track on a flexible or rigid magnetic storage disk. In particular, a positioning system is described in U.S. Pat. No. 4,122,503 to Allan. This patent and the previously used systems do not describe or point out the unique features for accurately locating the center of a previously recorded magnetic track as described herein.